ci: add Python 3.11/3.12 matrix (ruff+pytest)

Author: asq-sheriff

.github/workflows/ci.yml

@@ -5,11 +5,14 @@ on:
 jobs:
   ci:
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: [ "3.11", "3.12" ]
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-python@v5
         with:
-          python-version: "3.12"
+          python-version: ${{ matrix.python-version }}
       - name: Install deps
         run: |
           python -m pip install --upgrade pip